The present invention relates generally to an aircraft weather information system and, in particular, to an apparatus and method for detecting and indicating severe weather conditions in real time.
One of the problems associated with either the landing at, or the taking off from, an airport which is not manned is the lack of pertinent and up-to-date information on the conditions at the airport. Such information includes real time weather information and other information which can be exclusive to particular airports.
When an aircraft approaches an airport for a landing, the pilot must know both the wind direction and the wind speed if he is to land safely. If the airport is uncontrolled, the pilot must first fly over the airport and observe the windsock to make a judgment as to the present wind direction. However, this is very wasteful as it often takes up to ten minutes of extra flying time to perform this maneuver. Also, this maneuver can be quite dangerous in the event of a low overcast.
In the landing of a jet aircraft, the present outside temperature should also be available to the pilot. A jet aircraft takes off and lands by its indicated air speed which is determined by the weight of the aircraft and the outside temperature. If the pilot is not informed of the present outside temperature, he must estimate this temperature in order to determine the indicated air speed of the aircraft. A miscalculation of the indicated air speed can result in a jet aircraft using a larger portion of the runway than is necessary. Thus, if the pilot of a jet aircraft is informed of the present outside temperature, he can determine the correct indicated air speed for landing and consequently use less runway and fuel.
One apparatus for providing an aircraft with weather information has been disclosed in U.S. Pat. No. 3,949,399. A weather transducer is connected to a recording system such that, when the pilot generates the appropriate control signal to the system, the weather information is transmitted to the pilot in speech form. However, this apparatus is not capable of analyzing the signals from the weather transducer to provide the pilot with information such as the variation in wind direction or the speed of the wind gusts.
The problem of obtaining real time weather information was solved by a system and method for transmitting airport weather information disclosed in U.S. Pat. No. 4,163,216 and in U.S. Pat. No. 4,295,139. The weather information is transmitted in speech form to the pilot of an aircraft. The method can also provide the pilot with other information which can be considered pertinent to either the landing or the taking off of the aircraft. The radio telephone equipment normally found on board the aircraft can be used to activate an information transmitter or the transmitter can be continuously or manually activated.
A system for implementing the above-identified method includes a microcomputer which is used to read and analyze data received from a group of weather sensors. The microcomputer analyzes data received from a wind direction sensor over a last predetermined time interval to determine a most prominent wind direction and a most prominent wind variation in wind direction. Data received from a wind speed sensor is analyzed in a similar manner to determine a most prominent wind speed and a most prominent wind gust. The wind information is then further classified into such categories as "calm" or "light and variable". Other weather information which can be transmitted to the aircraft includes barometric pressure and temperature. When the system transmitter is activated, the microcomputer individually addresses locations of a voice storage means to generate a message which is then transmitted to the aircraft.
A significant problem at both manned and unmanned airports is obtaining information with respect to rapid changes in the weather parameters. One condition brought about by rapid weather changes is a microburst or wind shear. In its most dangerous form, wind shear is manifested by an area of strong down draft winds which can severely interfere with an aircraft which is close to the ground such as during landing and takeoff. However, wind shear is accompanied by rapid and significant changes in weather conditions such as wind direction, wind speed, barometric pressure and air temperature. Currently, a Low Level Wind Shear Alert System (LLWSAS), which was developed by the Federal Aviation Administration, has been deployed at many airports. However, this system senses wind direction and wind speed only and then computes wind differences to identify those differences which are associated with fronts and microbursts in the immediate airport area.
Another condition brought about by rapid weather changes is clear air turbulence. An airplane flying into clear air turbulence can experience rapid changes in speed, direction and altitude which changes are dangerous to the safety of the airplane and its passengers and crew.
It is an object of the present invention to facilitate the take off and landing of an aircraft at an airport.
It is another object of the present invention to provide real time weather information to airport personnel and the pilot and/or crew of an aircraft.
It is a further object of the present invention to provide warning of clear air turbulence and/or microburst and/or wind shear conditions.